button {
    height: 40px;
    margin: 5px;
    flex: 1;
}

.key-item{
    display: flex;margin: 5px;
}
.key{
    width: 80px;
}
.board {
    display: flex;
    flex-direction: column;
    border: 2px solid red;
    border-radius: 5px;
    margin-top: 10px;
}
